BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Talks.cam//talks.cam.ac.uk// X-WR-CALNAME:Talks.cam BEGIN:VEVENT SUMMARY:An efficiency theory of complexity and related phenomena - Profess or John Hawkins\, University of Cambridge\, RCEAL and University of Califo rnia\, Davis. DTSTART:20071127T160000Z DTEND:20071127T173000Z UID:TALK8364@talks.cam.ac.uk CONTACT:Napoleon Katsos DESCRIPTION:In this talk I discuss the relationship between efficiency and complexity in language structure and language use. The notion of complex ity has received more attention than efficiency and there have been seriou s attempts to define metrics for it. I argue that these metrics are curre ntly of limited value. They do not succeed in defining the structural pre ferences of language use and of grammars that they are designed to predict . Instead I argue that efficiency is the primary concept that we should b e defining\, I outline some of the different ways in which efficiency is a chieved\, and I link degrees of complexity in performance and grammars to this larger theory of efficiency.\n\nTheories of linguistic complexity sha re the guiding intuition that "more [structural units/rules/representation s] means more complexity". This intuition has proved hard to define. See \, for example\, the lively debate in the papers of Linguistic Typology (2 001) Vol.5-2/3 responding to McWhorter's (2001) analysis of creoles as "th e ... simplest" linguistic systems. The discussion went to the heart of t he fundamental question: what exactly is complexity? and how do we defin e it?\n\nSome problems include:\nTrade-offs: simplicity in one part of th e grammar often results in complexity in another\; several illustrations will be given.\n\nOverall complexity: the trade-offs make it difficult to give an overall assessment of complexity\, resulting in unresolvable deba tes over whether some grammars are more complex than others\, when there i s no clear metric of overall complexity for deciding the matter. \n\nDefin ing grammatical properties: the (smaller) structural units of grammars ar e often clearly definable\, but the rules and representations are anything but and theories differ over whether they assume "simplicity" in their su rface syntactic structures (see e.g. Culicover & Jackendoff 2005)\, or in derivational principles (as in Chomsky 1995)\, making quantification of co mplexity difficult in the absence of agreement over what to quantify.\n\nD efining complexity itself: should our definition be stated in terms of ru les or principles that generate the structures of each grammatical area (i .e. in terms of the "length" of the description or grammar\, as discussed most recently and extensively in Dahl 2004)\, or in terms of the structure s themselves (the outputs of the grammar)? Definitions of this latter kin d are inherent in metrics such as Miller & Chomsky's (1963) using non-term inal to terminal node ratios\, and in Frazier's (1985)\, Hawkins' (1994/20 04) and Gibson's (1998) metrics. Do these rule-based and structure-based definitions give the same complexity ranking or not?\n\nI argue that we ca n solve some of these problems if metrics of complexity are embedded in a larger theory of efficiency. Efficiency relates to the basic function of language\, which is to communicate information from the speaker (S) to the hearer (H). I propose the following definition:\n\nCommunication is effi cient when the message intended by S is delivered to H in rapid time and with minimal processing effort\;\n\nand the following hypothesis:\n\nActs of communication between S and H are generally optimally efficient\; tho se that are not occur in proportion to their degree of efficiency.\n\nCom plexity metrics\, by contrast\, are defined on the grammar and structure o f language. An important component of efficiency often involves structura l and grammatical simplicity. But sometimes efficiency results in greater complexity. And it also involves additional factors that determine the s peaker's structural selections\, leading to the observed preferences of pe rformance\, including:\n\nspeed in delivering linguistic properties in on- line processing\;\n\nfine-tuning structural selections to (i) frequency of occurrence and (ii) accessibility\;\n\nfew on-line errors or garden paths .\n\nThese factors interact\, sometimes reinforcing sometimes opposing one another. In Hawkins (1994\, 2004) I have presented evidence that grammat ical conventions across languages conventionalize these performance factor s and reveal a similar interaction and competition between them. Comparin g grammars in terms of efficiency\, rather than complexity alone\, gives u s a more complete picture of the forces that have shaped grammars and of t he resulting variation (including creoles). Cross-linguistic variation pa tterns also provide quantitative data that can be used to determine the re lative strength of different factors and the manner of their interaction w ith one another. \n\nReferences\n\nChomsky\, N. (1995). The Minimalist Pro gram. Cambridge\, Mass.: MIT Press.\n\nCulicover\, P.W. & Jackendoff\, R. (2005). Simpler Syntax. Oxford: Oxford University Press.\n\nDahl\, Ö. (20 04). The Growth and Maintenance of Linguistic Complexity. Amsterdam: John Benjamins.\n\nFrazier\, L. (1985). Syntactic complexity. In: D. Dowty\, L. Karttunen & A. Zwicky\, eds.\, Natural Language Parsing. Cambridge: Cambr idge University Press.\n\nGibson\, E. (1998). Linguistic complexity: Local ity of syntactic dependencies. Cognition 68:1-76.\n\nHawkins\, J.A. (1994 ). A Performance Theory of Order and Constituency. Cambridge: Cambridge Un iversity Press.\n\nHawkins\, J.A. (2004). Efficiency and Complexity in Gra mmars. Oxford: Oxford University Press.\n\nMcWhorter\, J. (2001). The worl d's simplest grammars are creole grammars. Linguistic Typology 5: 125-166. LOCATION:GR-06/07\, English Faculty Building END:VEVENT END:VCALENDAR